#738 Fix wrong URL in GrafanaCloudHostedMetrics

[gajewskiArek]

The issue or feature being addressed

#738

Details on the issue fix or feature implementation

The problem describe in original issues exists because we have following code:
var response = await _client.PostAsync("/metrics", content, cancellationToken);
client is initialized with your Url which looks like :
"https://graphite-prod-01-eu-west-0.grafana.net/graphite"

then when you inspect the request in f.e. fidler you would expect the payload to be sent to https://graphite-prod-01-eu-west-0.grafana.net/graphite/metrics. In fact is sent to https://graphite-prod-01-eu-west-0.grafana.net/metrics

this behavior of http is described here:
https://stackoverflow.com/questions/23438416/why-is-httpclient-baseaddress-not-working

the provided fix makes we're pushing the metrics to the address that grafana cloud expects

Confirm the following

• [X ] I have ensured that I have merged the latest changes from the dev branch
• I have successfully run a local build
• I have included unit tests for the issue/feature
• [X ] I have included the github issue number in my commits

[chinwobble]

I'm having the same issue. Could we get this merged?

[sabesam]

I have the same problem